Plunger-inserting machine



Jan. 4, 1955 c. A. HEISTERKAMP EI'AL 2,593,478

PLUNGEIR- INSERTING MACHINE 3 Sheets-Sheet 1 Filed May 15, 1951 l i I H Rx f/TTORNEY 1955 c. A. HEISTERKAMP ETAL 2,693,478

PLUNGER- INSERTING MACHINE 2 Wm 1% a h m m 6 m a m .v. 2 MmJflW a mg a MM? 3 IiT Filed May 15. 1951 HTTUR'NE) Jan. 4, 1955 c. A. HEISTERKAMP ETAL PLUNGER-INSERTING MACHINE Filed May 15. 1951 3 Sheets-Sheet 3 HHHHHHHH 1 United States Patent lice PLUNGER-INSER'HNG MACHINE Charles A. Heisterkarnp, Wynnewood, Warn G. Menhennett, West Chester, and Morris Dann and John Harpul, Philadelphia, Pa, assignors, by mesne assignments, to American Home Products Corporation, lew York, N. Y., a corporation of Delaware Application May 15, 1951, Serial No. 226,482

1 Claim. (31. 29-208 This invention relates to a plunger-inserting machine. More particularly it relates to a machine for inserting plungers or plugs, such a resilient rubber plungers, into tubes, such as glass tubes, as in the assembly of containers for prepared doses of parenteral therapeutic agents. One example of such assembly is the assembly of the device sold underv the name Tubex by Wyeth, Inc., Philadelphia, Pa.

This device incorporates an open-ended glass tube having a slidable rubber plunger in one end and a penetrable fixed plug in the other; a measured sterile dose is retained between the plunger and the plug. In use the tube is mounted in a frame, a hollow sterile needle is inserted in the frame in such a Way as to pierce the fixed plug, and the dose is expelled through the needle by endwise pressure on a rod bearing on the resilient plunger.

Our machine is primarily adapted to insert the slidable plungers in the glass tubes as a first step in assembling this device, and it inserts these plungers to a predetermined depth, thus providing a definite volume for filling the tubes in a subsequent operation. This increases accuracy of filling and reduces waste caused by overfill.

By suitable modifications, which will be clear to those skilled in the art from the following description, our machine can be used for a similar operation with other plungers or plugs and other tubes. The following description is thus to be taken as illustrative only and not as limiting our invention, the scope of which is defined in the appended claim.

Our machine comprises a fluted plungeror plug-feed Wheel and a fluted tube-feed wheel rotating in the same rotational direction on parallel axes. The plunger-feed wheel is mounted above and close to but not touching the tube-feed wheel. Each flute of the plunger-feed wheel is charged in turn with a plunger and each flute of the tube-feed wheel with a tube. Means are provided as the wheels rotate for dropping one plunger into each flute of the tube-feed wheel at the point of near tangency of the wheels, and for loading one tube into each such flute. The plunger and tube are positioned in each flute so that the plunger may be pushed along the axis of the flute into the tube.

The tube-feed wheel is provided on one side with a set of springbias ed push rods, one opposite each flute. This wheel revolves between a fixed cam on the side of the push rods and a spring-loaded flat plate on the opposite side. The cam is so placed as to force each push rod in turn inward towards the wheel against the pressure of its associated spring and thereby press a plunger into a tube. The spring-loaded plate receives the thrust of this pressure.

A suitable foundation, drive means, feed means, discharge means, scavenging means, and the like are provided as described in detail below.

In the drawings Fig. 1 is a general perspective view of the apparatus from the side and rear;

Fig. 2 is a rear view of the apparatus;

Fig. 3 is a horizontal section on the line 33 of Fig. 2;

Fig. 4 is a vertical section on the line 44 of Fig. 3;

Fig. 5 is a sectional detail on the line 5--5 of Fig. 4; and

Figs. 6, 7 and 8 are sectional views of the tube-feed wheel flutes showing the action of the push rods in three different positions.

A table 1 supports a frame 2 on which is mounted an Patented Jan. 4,. 1955 upper frame 3. The latter supports a tray 4 and the bearings 5 and 6 of the plunger-feed wheel 10 provided with peripheral flutes 11. With each flute is associated a right-angled air port 13 opening at one end into the base of the flute and at the other into the side of the wheel. Wheel 10 is rotated by chain 12 passing over sprocket 14, fixed on shaft 15 of the wheel. Adjustable idler 16 regulates the tension of the chain.

Bearings 17 and 18, mounted on frame 2, support shaft 19 of tube-feed wheel 20. The face of this wheel, broader than that of wheel 10, is provided with flutes 21. Its shaft 19 is provided at one end with sprocket 22, engaging chain 12, and at the other end with drive sprocket 23. The latter engages a chain which is driven by suitable connections with a conventional electrically driven variable-speed device.

The glass tubes 31 have an open end 32 with an aperture of the same diameter as the cylindrical bore, and an opposite open end 33 of restricted diameter- The resilient plungers 34 are provided with circumferential flutes 35 and a threaded brass stub stem 36. The diameter of the plungers is such that they are a tight sliding fit in the tubes. The inside diameter of the tubes is approximately 7 mm. and their length approximately 45 mm. The plungers are fed to the machine lubricated with a slight surface film of glycerine.

Mounted adjacent tube-feed wheel 20 is tube hopper 46, the rear wall 41 of which slants downwards to a bottom outlet 42 close to the rim of wheel 20. The opposing front wall 43 also converges on the bottom outlet. The dimensions of hopper are such that tubes 31 lie crosswise in it and feed by gravity to the bottom outlet 42, which passes one and only one tube at a time into each flute 21 of wheel 26 as it passes by.

An arcuate shield 44, mounted on slide 47, so as to be adjustable radially with respect to wheel 2 is provided to retain tubes and plungers in flutes of wheel 29 as rotation carries them to the under side of the wheel, and a similar arcuate shield 45 performs the same function for the plungers carried by wheel 10.

A broad flange 46 is fixed on wheel 20 in which are slidably mounted push rods 50; each push rod has a follower head 51 and is provided with a compression spring 52. The follower heads are adapted to bear against fixed cam 69 on rotation 'of wheel 20, the rods being thereby displaced lengthwise towards flutes 21 against the pressure of springs 52 as shown at a in Figs. 1 and 2. Associated with wheel 26 is pressure plate 70 mounted on frame 2 on the side of wheel 20 remote from cam 66 and opposite this cam in a position to receive the thrust of tubes 31 as the plungers are inserted. This plate is mounted in a fixed position with respect to the rotation of wheel 20, but is yieldably pressed towards the wheel by spring 72 with sufiicient force to withstand insertion of plungers into the glass tubes. If, however, a tube is wrongly oriented in flute 21 so that a plunger cannot be inserted, or if a foreign object finds its way into a flute, spring 72 yields, thus preventing breakage of the glass tube and the mis-oriented tube is carried onward by the wheel in the same manner as a correctly oriented tube. The correctly oriented tube with inserted plunger is carried onwards by the wheel until it passes the end of shield 41, where assembled tube and plunger are dropped by gravity into a receiver (not shown).

Associated with wheel 10, adjacent its point of near tangency with wheel 20 is a fitting 73 having an air port 74 so placed as to register in turn with the side opening of each duct 13. The port is connected by tube 75 with a source of low-pressured compressed air and the fitting bears resiliently and substantially airtight against the side face of wheel 10 through which ducts 13 open. The result is that as each duct 13 passes port 74, a puff of air is projected through the duct and dislodges any plunger in the associated flute.

Associated with wheel 20 is a fixed nozzle 76 connected by tube 77 with a source of low-pressure compressed air. The nozzle is aimed at the periphery of Wheel 20 at a point following its normal discharge point, and its effect is to scavenge flutes 21 of any adventitious bits of broken glass or other foreign matter by means by a continuous air blast before the flutes are again loaded.

In the illustrated embodiment of our invention, wheel is provided with 60 flutes and rotates at 1 R. P. M., and wheel 20 is provided with 20 flutes and rotates at 3 R. P. M. The output of the machine is thus one assembled tube-and-plunger per second. Sprocket 24 is fixed to shaft by a shear pin which yields if wheel 10 jams owing to an imperfect plunger. 1

In operation, one operator places plungers, from a supply on tray 4, manually in the flutes 11 of wheel 10 as the latter rotates, orienting the stub stems 36 towards the push-rod 50 side. Another operator keeps hopper 40 supplied with tubes 31, orienting them with wide opening 32 towards the push-rod side.

As each flute 11 of wheel 10 comes opposite air port 74, a puff of air through duct 13 assists gravity in releasing a plunger which falls into a flute 21 of wheel 20.

Wheel 10 is so positioned thatthe plunger falls into the,

push-rod end of flute 21. Each flute 21 after receiving a plunger then picks up a tube from hopper 40, the tube being located in the flute with its wide end towards the plunger as shown in Fig. 6. Thereafter the rotation of wheel activates the push-rod 50 associated with the loaded flute by means of cam 60, forcing the plunger into the tube by lengthwise movement of the push-rod. After the push-rod passes cam 60, spring 52 returns it to its original positi0n, and the assembled plunger and tube drop into a container (not shown) on table 1. The emptied. flute then passes the scavenging air stream from nozzle 76 and is prepared for a repetition of the cycle.

We claim:

A machine for inserting resilient plungers in glass tubes of uniform size to delimit a predetermined volume between the inner end of each plunger and the distal end of each tube, which comprises: a fluted plunger-feed wheel continuously revolving on a horizontal axis and adapted to receive a resilient plunger in each flute at a point near the top of its travel, a fluted tube-feed wheel continuously rotating on a horizontal axis lower than the axis of the plunger-feed wheel, each flute of the tubefeed wheel having a relatively deeper portion to accommodate a tube and a relatively shallower portion to accommodate a plunger in line with the bore of the tube, and the peripheries of the two wheels beingclose but not touching at a point of near tangency, means for continuously rotating the two wheels in the same rotational direction in timed relation such that a flute of one wheel passes the point of near tangency simultaneously with a flute of the other wheel, air-jet means for ejecting a plunger from a flute of the plunger-feed wheel into a flute of the tube-feed wheel at the point of near tangency, said air-jet means comprising a radial air duct communieating with each flute of the plunger-feed wheel at one end and with a port in the side of the Wheel at the other end and a slideable compressed air pipe spring-biassed against the port side of the plunger-feed wheel in a position to cover each port and deliver a jet of air thereto at the point of near tangency, means for loading each flute of the tube-feed wheel at a point near the top of its travel with a tube in a position to receive the plunger ejected into that flute, a spring-loaded push rod alined with each flute of the tube-feed wheel and carried by that wheel, a fixed cam mounted adjacent the tube-feed wheel and adapted to displace lengthwise for a predetermined distance the push rods carried by the latter against the spring loading of the rods at a location in the rotation of the tube-feed wheel at which the associated flute contains a plunger and a tube and in a direction to force the plunger into the tube, and a plate mounted on the side of the tube-feed wheel opposite the fixed cam to receive the thrust of the push rods, the plugs and the tubes, the mounting of said plate being such as to hold it in a fixed position with relation to the rotation of the tube-feed wheel but to permit it to yield resiliently in a direction parallel to the axis of said wheel when subjected to a thrust greater than that necessary to force a plunger into a tube, whereby in normal operation a uniform volume is delimited between the inner end of each plunger and the distal end of each tube and, in case of mis-orientation of plunger and tube, breakage of the tube is avoided.

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